po2tmx does not export plural strings

[jordimas]

translate-toolkit version 3.3.4

When exporting from PO 2 TMX the plural strings are NOT exported. I will expect these strings to be exported since they are valid segments.

In the attache files, the PO entry.

msgid "Backup was successful. %1 incidence was saved."
msgid_plural "Backup was successful. %1 incidences were saved."
msgstr[0] ""
"Il salvataggio della copia di sicurezza è riuscito. È stata salvata %1 "
"occorrenza."
msgstr[1] ""
"Il salvataggio della copia di sicurezza è riuscito. Sono state salvate %1 "
"occorrenze."

Is exported in TMX as:

 <tu>
      <tuv xml:lang="en">
        <seg>Backup was successful. %1 incidence was saved.</seg>
      </tuv>
      <tuv xml:lang="ca">
        <seg>Il salvataggio della copia di sicurezza è riuscito. È stata salvata %1 occorrenza.</seg>
      </tuv>
    </tu>

As you can see, the plural segment is not exported.

To reproduce the issue:

1. Use the files ca.zip
2. Run: po2tmx ca.po -o ca.tmx -l ca